US2508600A - Gypsum plaster composition - Google Patents
Gypsum plaster composition Download PDFInfo
- Publication number
- US2508600A US2508600A US769319A US76931947A US2508600A US 2508600 A US2508600 A US 2508600A US 769319 A US769319 A US 769319A US 76931947 A US76931947 A US 76931947A US 2508600 A US2508600 A US 2508600A
- Authority
- US
- United States
- Prior art keywords
- gypsum
- plaster
- plaster composition
- setting
- gypsum plaster
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000203 mixture Substances 0.000 title description 9
- 239000011507 gypsum plaster Substances 0.000 title description 7
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Inorganic materials [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 9
- 239000011505 plaster Substances 0.000 description 9
- 229910052602 gypsum Inorganic materials 0.000 description 7
- 239000010440 gypsum Substances 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 4
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 3
- 239000000920 calcium hydroxide Substances 0.000 description 3
- 235000011116 calcium hydroxide Nutrition 0.000 description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 3
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 3
- 239000001509 sodium citrate Substances 0.000 description 3
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229940037003 alum Drugs 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000005304 optical glass Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 1
- 229910052939 potassium sulfate Inorganic materials 0.000 description 1
- 235000011151 potassium sulphates Nutrition 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
- C04B28/16—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements containing anhydrite, e.g. Keene's cement
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/10—Accelerators; Activators
- C04B2103/12—Set accelerators
Definitions
- This invention relates to gypsum plaster composition and more particularly to a so-called blocking plaster possessing the necessary properties required for holding optical articles while being ground.
- calcined gypsum Although calcined gypsum has been widely used in the industry for this purpose, its faults do not permit its use in precision work Where great accuracy is essential. Ordinary calcined gypsum known as plaster of Paris has a very high expansion during setting, this being in the order of from 0.002" to 0.0025" per inch, produces a temperature rise of 30 to 40 F. during the process of setting, and develops a comparatively high early strength which increases greatly'on drying.
- alpha gypsum In the case of steam calcined gypsum known in the art as alpha gypsum, it has an even higher expansion during setting, this being about 0.005" per inch, as well as developing a higher temperature during setting of about 50 F., and a higher early and final strength. For these reasons alpha gypsum is unsuitable in the practice of the present invention.
- a high degree of expansion during setting is very likely to force the object to be ground out of position, thereby causing inaccurate grinding.
- Another object is a plaster composition characterized by a low temperature rise during the setting phase.
- a still further object is a plaster composition possessing medium strength when set.
- Terra alba acts as an accelerator and is added to control the time of setting. If desired, such salts as potassium sulfate, ammonium sulfate, nitre cake, alum or the like may also be added to control the setting time.
- a plaster composition made in accordance with the above formula has a total temperature rise during setting of 20 to 25 R, an expansion of from about 0.00015" to 0.00025" per inch during setting, and is of such strength that the optical articles are firmly held during the grinding or polishing operation but may be readily removed without breakage when the operation is complete.
- a gypsum plaster composition comprising 650 to 1,000 parts by weight -of plaster of Paris, 150 to 250 parts by weight of anhydrous gypsum, 25 to 50 parts by weight of terra alba, 10 to 20 parts by weight of hydrated lime, and 1 to 3 parts by weight of sodium citrate.
Description
Patented May 23, 1950 GYPSUM PLASTER COMPOSITION John J. Fitzsimmons, Clarence Center, N. Y., as-
signor to National Gypsum Company, Buffalo, N. Y., a corporation of Delaware No Drawing. Application August 18, 1947, Serial No. 769,319-
1 Claim. 1
This invention relates to gypsum plaster composition and more particularly to a so-called blocking plaster possessing the necessary properties required for holding optical articles while being ground.
Although calcined gypsum has been widely used in the industry for this purpose, its faults do not permit its use in precision work Where great accuracy is essential. Ordinary calcined gypsum known as plaster of Paris has a very high expansion during setting, this being in the order of from 0.002" to 0.0025" per inch, produces a temperature rise of 30 to 40 F. during the process of setting, and develops a comparatively high early strength which increases greatly'on drying.
In the case of steam calcined gypsum known in the art as alpha gypsum, it has an even higher expansion during setting, this being about 0.005" per inch, as well as developing a higher temperature during setting of about 50 F., and a higher early and final strength. For these reasons alpha gypsum is unsuitable in the practice of the present invention.
These are all factors which determine the usefulness of the material employed. The high temperature developed during setting is quite likely to change the physical characteristics of the optical glass and, in addition, melt the parafline which protects the same.
A high degree of expansion during setting is very likely to force the object to be ground out of position, thereby causing inaccurate grinding.
Since the optical article is eventually removed from the plaster in which it is embedded, a plaster having too great a strength would make removal difficult and likely cause damage during this operation.
It is, therefore, the object of this invention to provide a plaster composition having a greatly reduced rate of expansion upon setting.
Another object is a plaster composition characterized by a low temperature rise during the setting phase.
A still further object is a plaster composition possessing medium strength when set.
These and other objects of the invention will be apparent when reference is made to the description thereof which follows:
It has been found that a plaster composition containing the following ingredients in the range of proportions indicated is a useful blocking plaster for precision optical work.
2 Material: Parts by weight Calcined gypsum (plaster of Paris) 650-1,000 Anhydrous gypsum (Keenes cement) 250 Terra alba 25- 50 Hydrated lime 10- 20 Sodium citrate l 3 The anhydrous gypsum acts to reduce the temperature rise during setting, to reduce expansion,
and to lower early strength. Both the hydrated lime and the sodium citrate further reduce expansion during setting. Terra alba acts as an accelerator and is added to control the time of setting. If desired, such salts as potassium sulfate, ammonium sulfate, nitre cake, alum or the like may also be added to control the setting time.
A plaster composition made in accordance with the above formula has a total temperature rise during setting of 20 to 25 R, an expansion of from about 0.00015" to 0.00025" per inch during setting, and is of such strength that the optical articles are firmly held during the grinding or polishing operation but may be readily removed without breakage when the operation is complete.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is;
A gypsum plaster composition, comprising 650 to 1,000 parts by weight -of plaster of Paris, 150 to 250 parts by weight of anhydrous gypsum, 25 to 50 parts by weight of terra alba, 10 to 20 parts by weight of hydrated lime, and 1 to 3 parts by weight of sodium citrate.
JOHN J. FITZSIMMONS.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,960,538 Hoggatt May 29, 1934 2,216,555 King Oct. 1, 1940 2,358,701 Gardner Sept. 19, 1944 2,416,035 Whittier Feb. 18, 1947 FOREIGN PATENTS Number Country Date 783,074 France 1935
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US769319A US2508600A (en) | 1947-08-18 | 1947-08-18 | Gypsum plaster composition |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US769319A US2508600A (en) | 1947-08-18 | 1947-08-18 | Gypsum plaster composition |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2508600A true US2508600A (en) | 1950-05-23 |
Family
ID=25085104
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US769319A Expired - Lifetime US2508600A (en) | 1947-08-18 | 1947-08-18 | Gypsum plaster composition |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2508600A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3069278A (en) * | 1957-08-19 | 1962-12-18 | Aerojet General Co | Cement composition |
| US3189511A (en) * | 1962-11-23 | 1965-06-15 | Nat Gypsum Co | Gypsum wallboard |
| US3284227A (en) * | 1962-12-06 | 1966-11-08 | Fibreboard Paper Products Corp | Catalyzed gypsum wallboard and method of production thereof |
| US4081283A (en) * | 1976-02-23 | 1978-03-28 | Pmcma Research Group | Plaster molding composition |
| US4445937A (en) * | 1981-09-18 | 1984-05-01 | Ruhrkohle Ag | Pneumatic stowing of construction material comprising calcium alpha- and beta-sulphate hemihydrates |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1960538A (en) * | 1932-03-25 | 1934-05-29 | Certain Teed Prod Corp | Process of producing cementitious material |
| FR783074A (en) * | 1934-12-21 | 1935-07-08 | Ig Farbenindustrie Ag | Process to slow down the setting of hydraulic binders |
| US2216555A (en) * | 1937-11-26 | 1940-10-01 | United States Gypsum Co | Set-stabilized calcined gypsum plaster |
| US2358701A (en) * | 1941-03-06 | 1944-09-19 | Certain Teed Prod Corp | Hydraulic composition |
| US2416035A (en) * | 1944-09-21 | 1947-02-18 | United States Gypsum Co | Gypsum compositions capable of setting at elevated temperatures |
-
1947
- 1947-08-18 US US769319A patent/US2508600A/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1960538A (en) * | 1932-03-25 | 1934-05-29 | Certain Teed Prod Corp | Process of producing cementitious material |
| FR783074A (en) * | 1934-12-21 | 1935-07-08 | Ig Farbenindustrie Ag | Process to slow down the setting of hydraulic binders |
| US2216555A (en) * | 1937-11-26 | 1940-10-01 | United States Gypsum Co | Set-stabilized calcined gypsum plaster |
| US2358701A (en) * | 1941-03-06 | 1944-09-19 | Certain Teed Prod Corp | Hydraulic composition |
| US2416035A (en) * | 1944-09-21 | 1947-02-18 | United States Gypsum Co | Gypsum compositions capable of setting at elevated temperatures |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3069278A (en) * | 1957-08-19 | 1962-12-18 | Aerojet General Co | Cement composition |
| US3189511A (en) * | 1962-11-23 | 1965-06-15 | Nat Gypsum Co | Gypsum wallboard |
| US3284227A (en) * | 1962-12-06 | 1966-11-08 | Fibreboard Paper Products Corp | Catalyzed gypsum wallboard and method of production thereof |
| US4081283A (en) * | 1976-02-23 | 1978-03-28 | Pmcma Research Group | Plaster molding composition |
| US4445937A (en) * | 1981-09-18 | 1984-05-01 | Ruhrkohle Ag | Pneumatic stowing of construction material comprising calcium alpha- and beta-sulphate hemihydrates |
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